URL: https://bugzilla.kernel.org/show_bug.cgi?id=97191 Lukas Lueg 2015-04-23 22:20:35 UTC Running btrfs-progs v3.19.1 The btrfs-image attached to this bug causes the btrfs-userland tool to overflow some data structures, leading to unallocated memory being written to and read from. A segfault results shortly after. Reproduced on x86-64 and i686. The kernel seems to be less affected and fails to mount the image. I didn't investigate whether the reads/writes could be used to gain control over $EIP. Since the first invalid write of 8 bytes seems to run into adjacent heap blocks (crash in unlink()), it may be possible though. gdb output: Program received signal SIGSEGV, Segmentation fault. malloc_consolidate (av=av@entry=0x32629b7cc0 ) at malloc.c:4151 4151 unlink(av, p, bck, fwd); (gdb) bt #0 malloc_consolidate (av=av@entry=0x32629b7cc0 ) at malloc.c:4151 #1 0x0000003262680628 in _int_malloc (av=av@entry=0x32629b7cc0 , bytes=bytes@entry=4224) at malloc.c:3420 #2 0x000000326268315e in __GI___libc_malloc (bytes=4224) at malloc.c:2896 #3 0x0000000000449d15 in __alloc_extent_buffer (tree=0x88c078, bytenr=4288512, blocksize=4096) at extent_io.c:541 #4 0x000000000044a8b4 in alloc_extent_buffer (tree=0x88c078, bytenr=4288512, blocksize=4096) at extent_io.c:648 #5 0x000000000043b1a0 in btrfs_find_create_tree_block (root=root@entry=0x895840, bytenr=, blocksize=) at disk-io.c:159 #6 0x000000000043ca4e in read_tree_block (root=root@entry=0x895840, bytenr=, blocksize=, parent_transid=13) at disk-io.c:287 #7 0x000000000043ccb7 in find_and_setup_root (tree_root=0x88c250, fs_info=, objectid=5, root=0x895840) at disk-io.c:557 #8 0x000000000043ce92 in btrfs_read_fs_root_no_cache (fs_info=fs_info@entry=0x88c010, location=location@entry=0x7fffffffd960) at disk-io.c:640 #9 0x000000000043d060 in btrfs_read_fs_root (fs_info=fs_info@entry=0x88c010, location=location@entry=0x7fffffffd960) at disk-io.c:739 #10 0x000000000043d48c in btrfs_setup_all_roots (fs_info=fs_info@entry=0x88c010, root_tree_bytenr=, root_tree_bytenr@entry=0, flags=flags@entry=OPEN_CTREE_EXCLUSIVE) at disk-io.c:988 #11 0x000000000043d802 in __open_ctree_fd (fp=fp@entry=3, path=path@entry=0x7fffffffe20d "ramdisk/btrfs_fukked.bin", sb_bytenr=65536, sb_bytenr@entry=0, root_tree_bytenr=root_tree_bytenr@entry=0, flags=flags@entry=OPEN_CTREE_EXCLUSIVE) at disk-io.c:1199 #12 0x000000000043d965 in open_ctree_fs_info (filename=0x7fffffffe20d "ramdisk/btrfs_fukked.bin", sb_bytenr=sb_bytenr@entry=0, root_tree_bytenr=root_tree_bytenr@entry=0, flags=flags@entry=OPEN_CTREE_EXCLUSIVE) at disk-io.c:1231 #13 0x0000000000427bf5 in cmd_check (argc=1, argv=0x7fffffffdea0) at cmds-check.c:9326 #14 0x000000000040e5a2 in main (argc=2, argv=0x7fffffffdea0) at btrfs.c:245 valgrind output: ==32463== Memcheck, a memory error detector ==32463== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al. ==32463== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info ==32463== Command: btrfs check ramdisk/btrfs_fukked.bin ==32463== ==32463== Invalid write of size 8 ==32463== at 0x4386FB: btrfs_search_slot (ctree.c:1119) ==32463== by 0x4427F7: UnknownInlinedFun (extent-tree.c:3117) ==32463== by 0x4427F7: btrfs_read_block_groups (extent-tree.c:3167) ==32463== by 0x43D4F2: btrfs_setup_all_roots (disk-io.c:983) ==32463== by 0x43D801: __open_ctree_fd (disk-io.c:1199) ==32463== by 0x43D964: open_ctree_fs_info (disk-io.c:1231) ==32463== by 0x427BF4: cmd_check (cmds-check.c:9326) ==32463== by 0x40E5A1: main (btrfs.c:245) ==32463== Address 0x4c409f0 is 16 bytes after a block of size 144 alloc'd ==32463== at 0x4A08946: calloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) ==32463== by 0x4427AB: btrfs_read_block_groups (extent-tree.c:3162) ==32463== by 0x43D4F2: btrfs_setup_all_roots (disk-io.c:983) ==32463== by 0x43D801: __open_ctree_fd (disk-io.c:1199) ==32463== by 0x43D964: open_ctree_fs_info (disk-io.c:1231) ==32463== by 0x427BF4: cmd_check (cmds-check.c:9326) ==32463== by 0x40E5A1: main (btrfs.c:245) ==32463== ==32463== Invalid read of size 8 ==32463== at 0x436E70: check_block.part.14 (ctree.c:548) ==32463== by 0x438954: UnknownInlinedFun (kerncompat.h:91) ==32463== by 0x438954: btrfs_search_slot (ctree.c:1120) ==32463== by 0x4427F7: UnknownInlinedFun (extent-tree.c:3117) ==32463== by 0x4427F7: btrfs_read_block_groups (extent-tree.c:3167) ==32463== by 0x43D4F2: btrfs_setup_all_roots (disk-io.c:983) ==32463== by 0x43D801: __open_ctree_fd (disk-io.c:1199) ==32463== by 0x43D964: open_ctree_fs_info (disk-io.c:1231) ==32463== by 0x427BF4: cmd_check (cmds-check.c:9326) ==32463== by 0x40E5A1: main (btrfs.c:245) ==32463== Address 0x4c409f8 is 24 bytes after a block of size 144 in arena "client" ==32463== ==32463== Invalid read of size 4 ==32463== at 0x436E84: UnknownInlinedFun (ctree.h:1605) ==32463== by 0x436E84: UnknownInlinedFun (ctree.h:1612) ==32463== by 0x436E84: check_block.part.14 (ctree.c:550) ==32463== by 0x438954: UnknownInlinedFun (kerncompat.h:91) ==32463== by 0x438954: btrfs_search_slot (ctree.c:1120) ==32463== by 0x4427F7: UnknownInlinedFun (extent-tree.c:3117) ==32463== by 0x4427F7: btrfs_read_block_groups (extent-tree.c:3167) ==32463== by 0x43D4F2: btrfs_setup_all_roots (disk-io.c:983) ==32463== by 0x43D801: __open_ctree_fd (disk-io.c:1199) ==32463== by 0x43D964: open_ctree_fs_info (disk-io.c:1231) ==32463== by 0x427BF4: cmd_check (cmds-check.c:9326) ==32463== by 0x40E5A1: main (btrfs.c:245) ==32463== Address 0x4c409e4 is 4 bytes after a block of size 144 alloc'd ==32463== at 0x4A08946: calloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) ==32463== by 0x4427AB: btrfs_read_block_groups (extent-tree.c:3162) ==32463== by 0x43D4F2: btrfs_setup_all_roots (disk-io.c:983) ==32463== by 0x43D801: __open_ctree_fd (disk-io.c:1199) ==32463== by 0x43D964: open_ctree_fs_info (disk-io.c:1231) ==32463== by 0x427BF4: cmd_check (cmds-check.c:9326) ==32463== by 0x40E5A1: main (btrfs.c:245) ==32463== ==32463== Invalid read of size 1 ==32463== at 0x4A0B3A0: memcpy@@GLIBC_2.14 (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) ==32463== by 0x436E99: UnknownInlinedFun (ctree.h:1613) ==32463== by 0x436E99: check_block.part.14 (ctree.c:550) ==32463== by 0x438954: UnknownInlinedFun (kerncompat.h:91) ==32463== by 0x438954: btrfs_search_slot (ctree.c:1120) ==32463== by 0x4427F7: UnknownInlinedFun (extent-tree.c:3117) ==32463== by 0x4427F7: btrfs_read_block_groups (extent-tree.c:3167) ==32463== by 0x43D4F2: btrfs_setup_all_roots (disk-io.c:983) ==32463== by 0x43D801: __open_ctree_fd (disk-io.c:1199) ==32463== by 0x43D964: open_ctree_fs_info (disk-io.c:1231) ==32463== by 0x427BF4: cmd_check (cmds-check.c:9326) ==32463== by 0x40E5A1: main (btrfs.c:245) ==32463== Address 0x1b1 is not stack'd, malloc'd or (recently) free'd ==32463== ==32463== ==32463== Process terminating with default action of signal 11 (SIGSEGV) ==32463== Access not within mapped region at address 0x1B1 ==32463== at 0x4A0B3A0: memcpy@@GLIBC_2.14 (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) ==32463== by 0x436E99: UnknownInlinedFun (ctree.h:1613) ==32463== by 0x436E99: check_block.part.14 (ctree.c:550) ==32463== by 0x438954: UnknownInlinedFun (kerncompat.h:91) ==32463== by 0x438954: btrfs_search_slot (ctree.c:1120) ==32463== by 0x4427F7: UnknownInlinedFun (extent-tree.c:3117) ==32463== by 0x4427F7: btrfs_read_block_groups (extent-tree.c:3167) ==32463== by 0x43D4F2: btrfs_setup_all_roots (disk-io.c:983) ==32463== by 0x43D801: __open_ctree_fd (disk-io.c:1199) ==32463== by 0x43D964: open_ctree_fs_info (disk-io.c:1231) ==32463== by 0x427BF4: cmd_check (cmds-check.c:9326) ==32463== by 0x40E5A1: main (btrfs.c:245)